/*
 * Copyright (c) 2011-2015 Pivotal Software Inc., Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.camunda.bpm.extension.reactor.projectreactor.queue.internal;

/**
 * @author Stephane Maldini
 */
/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */


import org.camunda.bpm.extension.reactor.projectreactor.internal.PlatformDependent;

import java.io.Serializable;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;


abstract class MpscLinkedQueueHeadRef<E> extends MpscLinkedQueuePad0<E> implements Serializable {

  private static final long serialVersionUID = 8467054865577874285L;

  @SuppressWarnings("rawtypes")
  private static final AtomicReferenceFieldUpdater<MpscLinkedQueueHeadRef, MpscLinkedQueueNode> UPDATER;

  static {
    @SuppressWarnings("rawtypes")
    AtomicReferenceFieldUpdater<MpscLinkedQueueHeadRef, MpscLinkedQueueNode> updater;
    updater = PlatformDependent.newAtomicReferenceFieldUpdater(MpscLinkedQueueHeadRef.class, "headRef");
    if (updater == null) {
      updater = AtomicReferenceFieldUpdater.newUpdater(
        MpscLinkedQueueHeadRef.class, MpscLinkedQueueNode.class, "headRef");
    }
    UPDATER = updater;
  }

  private transient volatile MpscLinkedQueueNode<E> headRef;

  protected final MpscLinkedQueueNode<E> headRef() {
    return headRef;
  }

  protected final void setHeadRef(MpscLinkedQueueNode<E> headRef) {
    this.headRef = headRef;
  }

  protected final void lazySetHeadRef(MpscLinkedQueueNode<E> headRef) {
    UPDATER.lazySet(this, headRef);
  }
}
